Fix use-after-free of enum type id in Function::set_int_display_type

[ChrisKader]

Summary

Function::set_int_display_type converts the optional enumeration type id to an owned CString, then moves it into a map closure to take its pointer:

let enum_display_typeid = enum_display_typeid.map(IntoCStr::to_cstr);
let enum_display_typeid_ptr = enum_display_typeid
    .map(|x| x.as_ptr())            // moves the CString in, takes a pointer, then drops it
    .unwrap_or(std::ptr::null());
unsafe { BNSetIntegerConstantDisplayType(..., enum_display_typeid_ptr) }

The owned CString is dropped at the end of that closure, before the FFI call uses its pointer, so BNSetIntegerConstantDisplayType reads freed memory and stores a garbage type id.

Impact

Setting an integer operand to EnumerationDisplayType with a type id never resolves to the intended enumeration — the operand renders as a raw constant instead of the enumeration member. Confirmed by reading back the stored type id (garbage bytes) and by the operand failing to render the enum until this fix, after which it renders correctly.

Fix

Borrow the owned CString with .as_ref() so it lives until after the FFI call.